Wilkinson had done the right thing by resigning as labour minister, she said.

"A minister is responsible for her department. She's responsible for making sure it's properly resourced. There's big questions around that. There's been cuts to the Department of Labour going right back since she first became the minister.

"She is responsible for asking the hard questions and being on top of the portfolio and the issues.

"Going right back to 2009 she was not on top of the issues around mine safety."

Shearer said it was important the Government adopted the Commission's key recommendation to establish a stand alone agency responsible for mining.

"It will mean it is no longer submerged within a broader entity - Mobie (the Ministry of Business, Innovation and Employment) - which is about business and innovation.

'HONOURABLE THING'

Key said Wilkinson's resignation was the honourable thing to do.

He apologised to the families of the dead men but said much of the fault lay with the mine's owner, Pike River Coal.

The report found the effectiveness of the mining inspectorate had been run down over many years - and the DOL failed to pick up on a series of lethal failings at the mine.

It did not act to close the mine, near Greymouth, while adequate systems - for gas drainage, ventilation and emergency exits - were put in place.

Officials had assumed Pike River Coal was complying with health and safety laws ''even though there was ample evidence to the contrary,'' the report said.

The head of the ministry that has absorbed the Department of Labour said he accepted the findings of the royal commission.

David Smol, chief of Mobie, this morning promised urgent change in the wake of the damning report.

He said he was taking legal advice, and would make an announcement on staff matters when he had finished deliberating.

Acting labour minister Chris Finlayson, also the Attorney-General, avoided reporters this morning as he made his way to the National party's weekly caucus meeting.

Meanwhile, Key refused to rule out further heads rolling within the public service as a result of the tragedy.

Key said it was a matter for Smol whether more people would be held accountable over the former Labour Department's failings.

"I know he takes his responsibilities very seriously. I know the department is doing a lot of soul searching after the release of the royal commission report yesterday," he said.

"Let's wait and see but that's something in the fullness of time we will have a better understanding of."

Responsibility for protecting workers lay ultimately with the company but "in the end there was a situation where the Department of Labour also has to shoulder some of the responsibility here".

"They, over a long period of time, changed the way they did things. They had a very low touch model and, in fact, the advice they gave the minister was that not only were they happy with the way things were operating, but they were building capability.....I think you've got to say they actually have got that wrong."

Key also defended the decision not to strip Wilkinson of all her Cabinet portfolios.

"If there was a situation where we could go along and say Kate Wilkinson was a poor minister that failed to protect those workers of course that would be a very different situation. But I've never seen any paperwork or advice that supports that."